Valve unit for controlling double acting fluid operating cylinders

ABSTRACT

A system comprising a fluid motor and a valve unit, said valve unit having a movable slide valve connecting in its end positions one side of a fluid motor to a fluid source under pressure and the other side of said fluid motor to a sump or to the atmosphere and connecting in its central position both sides of said fluid motor to said fluid source under pressure, said valve unit having a shifting slide and solenoid valves actuating said slide. After de-energizing said solenoid valves, said slide valve is caused to move into its central position so that the fluid motor is immediately supplied with fluid under pressure via passages containing excess pressure valves and the slide on both sides and retained in every intermediate and end position.

United States Patent Hohlein 1 Dec. 25, 1973 {5 VALVE UNIT FDR CONTROLLING 3,313,316 4/1967 Thomas l37/596.l2 x DQUBLE ACTHNG m OPERATWG 3,315,702 4/1967 Passaggiom. 137/625.64 3,502,109 3/1970 Straight 137/625.64

CYLKNDERS [76] Inventor: Herman Heinlein, Planckstrasse 10,

Wolfsburg, Germany [22] Filed: July 15, 1970 [21] Appl. No.: 54,915

[52] 13.8. C1. 91/459, 91/461 [51] Int. Cl. F151) 111/08, F15b 13/043 [58] Field of Search 91/450, 451, 452,

[56] References Cited UNITED STATES PATENTS 2,729,242 1/1956 Olson 91/51 X 2,949,097 8/1960 Vander Kaay 137/625.68

3,062,192 11/1962 Webb 1. 91/51 X 2,980,136 4/1961 Krehbiel 91/451 X 3,129,645 4/1964 Olmsted 1 91/461 3,212,522 10/1965 Williams 137/596.12 3,269,417 8/1966 Lansky et al. l37/625.64

Primary Examiner-lrwin C. Cohen Attorney-Watson, Cole, Grindle & Watson [5 7 ABSTRACT A system comprising a fluid motor and a valve unit, said valve unit having a movable slide valve connecting in its end positions one side of a fluid motor to a fluid source under pressure and the other side of said fluid motor to a sump or to the atmosphere and connecting in its central position both sides of said fluid motor to said fluid source under pressure, said valve unit having a shifting slide and solenoid valves actuating said slide. After de-energizing said solenoid valves, said slide valve is caused to move into its central position so that the fluid motor is immediately supplied with fluid under pressure via passages containing excess pressure valves and the slide on both sides and retained in every intermediate and end position.

3 Claims, 3 Drawing Figures PATENTEU 3,780,623

summrg P m a" INVENTOR.

Hagan HoLZm'n PA1ENTEU 3,780,623

811E111 2 (If 2 IN V EN TOR.

Hfikgg van HOLZQLR A figs.

VALVE UNIT FOR CONTROLLING DOUBLE ACTING FLUID OPERATING CYLINDERS This invention relates to valves with a five-way, three-position slide for the control of double acting operating cylinders with pneumatic or hydraulic drive, the pistons of which can be stopped quickly upon operation of a proper protective device and can be held in this stop position.

It has been known to use valves with five-way, threeposition slides for the control of double acting operating cylinders. The middle position of the slide normally is used to arrest the operating piston. In a known structure both sides of the piston are acted upon in this middle position with the full network or grid system pressure, whereby a satisfactory stopping and stability of position cannot be achieved because the forces developing by outside weights and varying piston surfaces are not compensated for. In another design, all channels of the valve are closed in the middle stopping position of the slide, such valve to be sure exhibiting a good stopping behavior even for substantially large masses because a unilateral increase in the braking pressure is made possible. The resiliency resulting from such design is, however, undesirable and, moreover, because of a one-sided dead load or because of varying piston surfaces with accompanying leaks in the lines or in the piston, it is impossible to maintain the stop position. The greatest drawback of this valve, however, is that with continued travel after a prolonged stop position, the air necessary for the action of the exhaust air throttles and for the damping effect excapes because of leaks, thereby causing an unintended rapid movement.

A further disadvantage of the present valves with five-way, three-position slides is that in the event of an emergency stop, the cylinders of an installation are no longer capable to receive or absorb outside forces and will possibly leave their end position which they had already reached.

It is therefore an object of the invention to construct a valve to permit adjustment of the pressures in the sides of the cylinder necessary for a stable stop position of the operating piston so as correspond with the pertinent load and piston surface conditions in such a manner that the required equilibrium condition will be fulfilled and will be maintained even in the event of leakage. Besides, the piston must be capable of receiving outside forces in its end positions.

Further objects of the invention will become apparent from the following description when considered in connection with the accompanying drawings in which,

FIG. 1 is a sectional diagrammatic view of the valve system,

FIG. 2 is a sectional view of a modified valve system, and

FIG. 3 is a wiring diagram.

In the accompanying drawings FIGS. 1 and 2 are sectional views of two valves. The two valves will be described in connection with fulfilling those requirements relating to the aforementioned problem. The first valve, shown in FIG. ll, acts upon the sides of the cylinder in the stop position with the necessary equilibrium pressures. The second valve shown in FIG. 2, provides a unilateral pressure action in the end positions of the operating piston, as a result of which the piston is capable of receiving or absorbing outside forces. The

method of operation for both valves is independent from one another.

The structure of the valve will be now explained with reference to FIG. 1. The piston 2 of cylinder 1 provided with a weight 3 is controlled through a connecting plate 6 by means of a slide 10 movable in a housing 9. The upward movement, direction a, takes place due to the operation of the left-hand solenoid valve 19 by pressure in channel 17 in the left pre-control chamber by movement of slide It) to the right (direction x), toward spring 14 and stop 16, whereby chamber A in cylinder 1 will receive the full pressure in a distributor and chamber B is relieved via channel 3 and exhaust air throttle 8. The downward movement takes place in the same manner, but in the reverse direction through solenoid valve 20, pressure on channel 18 and on the righthand pre-control chamber, by movement of the slide 10 toward the left (direction y) against spring 13 and stop 15, as a result of which, pressure will reach side Y of cylinder 1, and the side X is relieved by means of channel R and exhaust air throttle 7. In a stopped position, neither of the solenoid valves 19 and 20 is energized. Channels 17 and 18 are relieved and spring 13 and 14 will move the slide into the middle position drawn.

New in this valve according to the invention, are the additional channels Al and A2 as well as B1 and B2, each intercommunicating only in the middle position with one another by means of the slide recesses 11 or 12, but which are blocked in the operating positions.

Furthermore, an additional pressure regulating unit 21 is provided which contains four excess pressure valves. The left-hand excess pressure valve, designed for good braking effect to the full nominal diameter and comprising a valve disk 25, spring 27, spring collar 29 and adjusting screw 31, ensures a quick buildup in braking pressure in the channel A2 up to a value adjustable through screw 31 which pressure, in the middle position of slide 10, acts by means of A2, A1 and channel 23 on side X of the cylinder. In the case of spring 27 unloaded, as shown, the full network or grid system pressure, for example, (5 kp/cm' is effective. An excess pressure valve is disposed within part 31 and comprises ball 33, spring 35 and adjusting screw 37, having a small diameter. Accordingly, a higher adjustment, for example (5.5 kplcm is possible for reducing any short-interval pressure increases which may develop during braking action, in such a manner that within a predetermined time, about I to 3 sec., after the time of stopping, the adjusted pressure will be reached and held in Al, A2 and A even when leaks occur. The two excess pressure valves with the parts 26, 28, 30, 32, 34, 36 and 38, arranged on the right have the same effect on channel B2 in the middle position of the slide and therefore also on cylinder side y. Because of the dead load 3, it will be necessary to reduce the pressure in B, for example,to (2.5 kp/cm), by tightening spring 28 and accordingly expanding of the spring 36 in order to fulfill the conditions of stability in the stopping position, whereby the small excess pressure valve will likewise have to be adjusted somewhat higher than the nominal pressure, for example, (3.0 kp/cm The large excess pressure valve is closed whenever the proper equilibrium pressure has built up in B. The small excess pressure valve has the object of reducing the full network or grid system pressure existing after preceding downward movement after a certain time l 3 sec.)

after the stopping action to the nominal pressure, for example, (3.0 kp/cm Therefore, it is possible with the slide valve described to stop any cylinder piston with a constant dead weight or unequal piston surfaces and to be able to hold it in the position achieved even in the case of leaks in the piston along the rod packing or in the lines or pipes as long as desired, whereby sufficient air is available for a restarting and for the good effect of the exhaust air throttles.

lnthe case of a nonconstant weight influence, movements of the crank lever or toggle lever, it is likewise possible to fulfill the equilibrium position for every cylinder position whenever the excess pressure valves are adjusted dependent upon the stroke correspondingly by curved or similar shaped means.

The second valve will now be described with reference to FIG. 2.

The. piston 102 of the cylinder 101 provided with a weight 103 is controlled through connecting plate 106 by a slide 110 movable within a slide housing 109, whereby in the middle position drawn, the piston 102 is braked down and held in the case of a leakproof or sealed system. Neither of the two end position switches 104 (position b) and 105 (position a) is operated.

For a downward movement in direction b, the slide l must assume the left-hand end position, whereby the channels P are connected with B and A with R, and the exhaustair throttle 107 determines the speed. In the downward position of the piston 102, the end position switch 104 will be operated.

In the same manner, but conversely, the upward movement is triggered in the direction a by the righthand end position of slide 100, whereby there exists a connection from P to A and from B to S with an adjustment in speed through the exhaust air throttle 108. In the upward position of the piston, the end position switch 105 is operated. The two additional pre-control or servo pistons, consisting of the parts 111, 113, 115 and 117 for the left-hand side and of the parts 1 12, 1 l4, 116v and 118 for the right-hand side, have been arranged on or in the ends of slide 110. As compared to the use of two springs in known slide designs, they serve to move slide 100 into the middle position by pressure on the pre-control chambers 1 23 and 125, as well as on the chambers 124 and 126. Pressure in the chambers 124 and 126 and relief of the chambers 123 and 125 brings about the left-hand slide position y. Conversely, pressure on 123 and 125 and relief of chambers 124 and 126 brings about the right-hand slide position x, the dimensions of the control surfaces having been intentionally designed such that surfaces F (D) are more than twice as large as surfaces f (d), so that the force corresponding to the surfaces F(D) minus f(d) for movement of the slide into the middle position there is larger than the force bringing about the end positions and corresponding to the surfaces f (d). With this measure, the assurance for reaching the middle position is considerably increased, because a sluggishly moving slide or a slide having a tendency to stick would not reach the end position with the smaller force, but it is to be assumed that with the greater force the middle position for stopping the piston will still be safely achieved.

A further important characteristic of the slide arranged in this manner is that it maintains its end position achieved at any one time through friction of the packings 113, 115, 114 and 116 when all control chambers 123, 125, 124 and 126 are without pressure. This characteristic is exploited for the stability of the end positions.

For a description of the function of the pre-control unit 164 and the solenoid valves 154, 155, 156 and 157, reference is made to FiGS. 2 and 3.

The pilot pressure comes from channel 1 through channel 131, the recess in packing 135, filter 133, channel 136, storage valve 146 standing in the lefthand position into the channel 143 and from there via the not-operated pilot valves 137 and 138 and via the channels 129 and 130 into the pre-control chambers 123 and or 124 and 126, as a result of which the middle position of the slide willbe achieved and the operating piston 102 will be stopped. Furthermore, there is pressure below the solenoid valves 154 and 155. All other channels are without pressure.

Now, if movement of the operating piston is to take place in the direction a, the solenoid valve 155 is energized by manual or automatic operation of the key 160, as a result of which pressure will reach the solenoid valve 157 which at first is still locked or closed. The pressure reaches the channel 148 as well as into the channel 127 via the throttle 140, which channel 127 is closed at its end by a middle position stop 117 acting simultaneously as a valve disk, so that the pressure can build up on the control piston of the pilot valve 138 which, as a result thereof, assumes the left-hand switching position. Thus the channel and the control chambers 124 and 126 are relieved so that the slide 1 10 and piston 112 will be shifted to the right toward stop 120 by the pressure in the chamber 125 appearing on the left, as a result of which the movement of piston 102 in direction a takes place. Disconnection of key or knob 160 again brings about the starting condition. Through short time manual operation, the piston 102 therefore can be moved into any desired position slowly by way of short partial movements.

Now, if piston 102 has reached its lowermost position with an energized solenoid valve 155 and operates the pilot end position switch 105, and thus the solenoid valve 157 is energized, channel 152, the right side of the OR member obtains pressure or is placed under pressure as a result of which channel 151 is closed. The large left-hand piston of the storage valve 146 is acted upon through channel 149 and said valve is pushed to the right, although pressure also appears on the right-hand small piston surface by means of the OR member 144 and channel 145. in this position the channel 143, channel 129 and the left-hand pre-control chambers 123 and 125 are relieved so that the end position x of the slide, and thus the pressure in chamber A is maintained. After a drop in pressure has taken place, the key 160 and the plug 161 or the energized switch 162 or the main switch 163 may be disconnected, whereby the channels 148, 127, 145, 152 and 149 and thus both sides of the storage valve 146, will be relieved through the solenoid valve and particularly also the solenoid valve 157, without however said storage valve changing its position. The right-hand end position of slide 100 thus will be maintained. The subsequent switching back of valve 138 will likewise be without any effect.

The piston 102 being under pressure in the end position A is therefore in a position now to absorb outside forces.

The movement of the operating piston 102 into the opposite or left hand direction is introduced by operation of key 159 and energizing of the solenoid valve 154. The pressure in channel 147 made possible by throttle 139 and the blocked nonreturn valve 141, will first of all have an effect on the right-hand small piston surface of the storage valve 146 via the OR member 144 blocking channel 143 and via the channel 145. Since the larger, left-hand piston surface is without pressure (solenoid valves 155 and 156 are not energized), the piston of valve 1 16 again assumes the lefthand position and the channel 143 obtains pressure or is put under pressure which also reaches the right-hand pre-control chambers 124 and 126 via the not operated valve 38 and channel 30. The left-hand pilot valve 137 will at first not yet be switched, because the channel 128 is still connected with the relief channel 122 in the pre-control chamber 124. Therefore, the chambers 123 and 125 also obtain pressure via pilot valve 137 and channel 129. The piston of the pre-control valve 112 with its stop 118 and the slide 110 therefore assume the middle position for a short time. Only when the channel 128 is closed by stop 118 acting as a valve packing and when the pressure is being built up, the valve 137 is shifted to relieve channel 129 and chambers 123 and 125, as a result of which slide 100 moves to the left because of the pressure in chamber 126 and causes the movement of piston 102 in the direction B. The opening of the end position switch 105 caused thereby and releasing of the solenoid valve 157 in that case remains without effect. Now at every point of the stroke a stop is possible again through opening of 159, 161, 162 or 163 and a short time actuation by way of key 159 is again possible. Only the end position switch 104 closing in the end position B again effectuates or brings about the right-hand position of the storage valve 146 by means of the solenoid valve 156 and the OR member 150, as a result of which slide 100 will maintain its position y because of relief on both sides, and the pressure prevailing in channel B also stabilizes piston 102 against outside forces in this end position with simultaneous relief of the piston side A. The counter movement can then be triggered again only by key 160, and solenoid valve 155 via back switching of the storage valve 146, middle position of the slide, shifting of valve 138 and by the movement of slide 100 to the right. At first this indeed seems to be a time consuming process. However, by correspondingly large dimensioning of valves 137, 138 and 146 as well as of channels 131, 136, 143, 129 and 130, it is possible to keep the time for this process within bearable limits.

The requirement that the perfect functioning of all movable parts must be the prerequisite for a normal operating function will be fulfilled in regard to the pilot pistons 111 and 112 necessary for the middle position by the last described method, in such a way that a counter movement can take place from the end position of the piston only when the middle position has been reached previously satisfactorily for a short period of time. If, for example, the valve 137 does not shift back, then the slide position B cannot be left. If it does not switch then position B will not be reached and the same thing is true for valve 138 with effects on position A.

Whenever storage valve 146 after operating the solenoid valves 154 or 155 does not shift back into the lefthand position, the slide 100 can no longer change its position because the control pressure is missing and a piston movement is no longer possible. If it does not shift toward the right in the end position of the piston, then there follows the harmless or not dangerous middle position after discontinuance of the approach, and in the case of an outside power effect on the piston 102, the latter will leave its end position and thus its pilot end position switch 104 or 105. This likewise leads to a harmless operational breakdown. If the solenoid valve 154 does not shift back in the stabilized end posi tion B of the cylinder, a shifting into the opposite direction A is no longer possible because the large left side of the storage valve 46 is still under pressure by means of 156, 151, 150 and 149, with the result that the storage valve 146 cannot be shifted back. The same is true accordingly for the solenoid valve 155.

Whenever the solenoid valve 156 or the end position switch 104 does no longer shift back, the movement in direction a and the stabilization in the uppermost position A is still possible, whereby the storage valve 46 has assumed its right-hand position. In the case of the next actuation of key 159 and solenoid valve 154 however, the storage valve 146 will receive pressure also on the large left-hand operating surface, so that it cannot shift to the left and a movement of slide 10 is no longer possible. Logically the same is true for the solenoid valve 157 and the end position switch 105. Thus the valve on the basis of the enumerated characteristics may be called intrinsically safe.

in order to keep away impurities in the pilot or operating medium which can disturb the function of the storage valve 146 executed predominantly as a slide without sealing, an exchangeable filter 133 has been provided.

By a turn of packing 135 through 180, it is possible moreover to feed in the pilot medium separately at the connection 134 of plate 132 whenever the main slide 110 is to be operated with a higher pressure.

In the case of use of the valve in purely pneumatic or hydraulic systems, the solenoid valve 54 and 155 may be omitted. The distribution then takes place directly to the channels 47 and 48. The solenoid valves 156 and 157 must then be replaced by valves that can be controlled pneumatically or hydraulically, and which then are operated by pilot end position valves. The function otherwise is the same.

Whenever the solenoid valve 154 or 155 fails to operate, no control takes place. If the solenoid valve 156 or 157 fails to operate, the same harmless effect is present as already described, as though the storage valve 146 is obstructed in its movement toward the right.

Thus the requirement has been fulfilled, namely, that the perfect functioning of all the movable parts is the prerequisite for the normal operation and that in the case of breakdowns a piston stroke is no longer possible or that stopping occurs.

For a further smooth operation, the valve therefore has to be exchanged. Beyond that, the perfect functioning of the pilot end position switches 104 and 105 will be checked by this valve during every operating cycle, because a movement out from an end position can be effected only when the end positions switch of the opposite end position is not operated. An electrical control, which in other instances is required, is not needed.

I claim:

1. A system comprising a fluid motor formed by a double acting operating cylinder having two pressure chambers on different sides of a piston a conduit connected to each of said pressure chambers, a five-way valve unit, said unit'comprising: channel means containing fluid under pressure; further channel means leading to exhaust means; a housing; a slide having recesses therein and being disposed for sliding movement in said housing, said fluid motor and said channel means and said further channel means being operatively interconnected via said conduits and said recesses in said slide, said channel means and said further channel means opening into said housing respectively through said recesses; spring means disposed in said housing in engagement with said slide for urging said slide along the direction of its axis and normally effecting a centered position of said slide; said housing on both end sides of said slide defining pre-control chambers; two solenoid valves provided to selectively connect, when selectively energized, said pre-control chambers to one of said channel means and said further channel means; stop means in said pre-control chambers defining two end positions for said slide, said slide moving into one of its end positions when one of said pre-control chambers is connected to said channel means and into the other of its end positions when the other of said pre-control chambers is connected to said channel means thereby selectively connecting one of said pressure chambers of said fluid motor to said channel means and the other of said pressure chambers to said further channel means; pressurized passages provided in said unit leading to said channel means; said slide blocks said passages from communication with said pressure chambers of said motor when said slide is moved to its end positions to operate said fluid motor, said slide being disposed at its centered position when both said solenoid valves are de-energized to thereby connect both said pressure chambers to said passages via said valve recesses; an excess pressure valve disposed in each of said passages at the connection with said channel means, each said excess pressure valve comprising a valve disk, a spring arranged to urge along with the pressure in its respective passage each said valve disk to close its respective passage against the pressure in said channel means such as to connect each said passage to said channel means only when the pressure in each said passage drops below a value individually determined by the force exerted on each said disk by its respective spring, whereby said fluid motor is stopped and retained in any intermediate and end position regardless of pertinent load conditions and leaks when both said solenoid valves are de-energized.

2. A system according to claim 1 wherein each of said excess pressure valves further comprises a valve body and a settable nut threadably engaging each said valve body, each said spring being arranged between said disk and said nut of each said excess pressure valve, the force exerted by each said spring on each said disk being adjustable by adjusting the setting of each said nut, these adjustments in both excess pressure valves being such that, with said slide in its central position, said piston of said fluid motor is balanced via the pressures insaid pressure chambers regardless of pertinent load conditions and leaks.

3. A system according to claim 2, wherein each of said excess pressure valves is provided with a relief valve for releasing excess pressure in each of said passages, said relief valve being housed in a bore provided in each said nut, and a spiral spring adjustable by means of a settable screw being provided for spring-biassing each said relief valve.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 7 62 D d December 25, 1973 I v t- Herman Hohlein It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the title page please insert --Claims priority on German application No. P 19 36 370.3, filed July l969-. u H H l I Signed and sealed this 17th day of September 1974.

(SEAL) 'Attest:

McCOY M. GIBSON JR. c. MARSHALL DANN Attesting Officer Commissioner of Patents USCOMM-DC 6O376-P69 us. GOVERNMEN! PRINYING OFFICE: 19:9 o-ass-au. 

1. A system comprising a fluid motor formed by a double acting operating cylinder having two pressure chambers on different sides of a piston a conduit connected to each of said pressure chambers, a five-way valve unit, said unit comprising: channel means containing fluid under pressure; further channel means leading to exhaust means; a housing; a slide having recesses therein and being disposed for sliding movement in said housing, said fluid motor and said channel means and said further channel means being operatively interconnected via said conduits and said recesses in said slide, said channel means and said further channel means opening into said housing respectively through said recesses; spring means disposed in said housing in engagement with said slide for urging said slide along the direction of its axis and normally effecting a centered position of said slide; said housing on both end sides of said slide defining pre-control chambers; two solenoid valves provided to selectively connect, when selectively energized, said pre-control chambers to one of said channel means and said further channel means; stop means in said pre-control chambers defining two end positions for said slide, said slide moving into one of its end positions when one of said pre-control chambers is connected to said channel means and into the other of its end positions when the other of said pre-control chambers is connected to said channel means thereby selectively connecting one of said pressure chambers of said fluid motor to said channel means and the other of said pressure chambers to said further channel means; pressurized passages provided in said unit Leading to said channel means; said slide blocks said passages from communication with said pressure chambers of said motor when said slide is moved to its end positions to operate said fluid motor, said slide being disposed at its centered position when both said solenoid valves are deenergized to thereby connect both said pressure chambers to said passages via said valve recesses; an excess pressure valve disposed in each of said passages at the connection with said channel means, each said excess pressure valve comprising a valve disk, a spring arranged to urge along with the pressure in its respective passage each said valve disk to close its respective passage against the pressure in said channel means such as to connect each said passage to said channel means only when the pressure in each said passage drops below a value individually determined by the force exerted on each said disk by its respective spring, whereby said fluid motor is stopped and retained in any intermediate and end position regardless of pertinent load conditions and leaks when both said solenoid valves are de-energized.
 2. A system according to claim 1 wherein each of said excess pressure valves further comprises a valve body and a settable nut threadably engaging each said valve body, each said spring being arranged between said disk and said nut of each said excess pressure valve, the force exerted by each said spring on each said disk being adjustable by adjusting the setting of each said nut, these adjustments in both excess pressure valves being such that, with said slide in its central position, said piston of said fluid motor is balanced via the pressures in said pressure chambers regardless of pertinent load conditions and leaks.
 3. A system according to claim 2, wherein each of said excess pressure valves is provided with a relief valve for releasing excess pressure in each of said passages, said relief valve being housed in a bore provided in each said nut, and a spiral spring adjustable by means of a settable screw being provided for spring-biassing each said relief valve. 